Bump maven-site-plugin from 3.8.2 to 3.9.0

Bumps [maven-site-plugin](https://github.com/apache/maven-site-plugin) from 3.8.2 to 3.9.0.
- [Release notes](https://github.com/apache/maven-site-plugin/releases)
- [Commits](apache/maven-site-plugin@maven-site-plugin-3.8.2...maven-site-plugin-3.9.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

pom.xml

@@ -52,7 +52,7 @@
         <maven.javadoc.plugin.version>2.7</maven.javadoc.plugin.version>
         <maven-jaxb2-plugin.version>0.8.2</maven-jaxb2-plugin.version>
         <maven.release.plugin.version>2.5.3</maven.release.plugin.version>
-        <maven.site.plugin.version>3.8.2</maven.site.plugin.version>
+        <maven.site.plugin.version>3.9.0</maven.site.plugin.version>
         <maven-source-plugin.version>3.0.1</maven-source-plugin.version>
         <maven-war-plugin.version>2.2</maven-war-plugin.version>
         <maven.assembly.plugin.version>3.2.0</maven.assembly.plugin.version>